Amplifying system



Amg. 111, 1925..

1,549587 H! B. MARVIN AMPLIFYING SYSTEM Filed Se t. 27. 1921 InVefltLor:

His Amoine 5- Petented Aug. 11, 1925.

ounce sures ifiidhii PATENT nann n. MARVIN, on sennuncmmr, new YORK, essrenon 'ro sciences npncrnro GOMPAN'Y, A conronerron on new Yonn'.

AMPLIFYING: SYfiTE'M.

Application filed September 27, 182E. Barrel 1%. screen.

To all whom it may concern:

Be it known that I, HAnurB. MAiivm, a citizenf the United States, residing at Sc enectod ,iii the county of Schenectady, State oi a ew York, have invented certain new and'useful Improvements in Amplifying Systems, of ,which thefollowing is a specification. My present invention'relates to apparatus for amplifyingsmall clternatingpotentials or currents and producing an indication of the amplified effects.

One of the objects of my" invention is to provide a simple and efficient apparatus for amplifying alternating currents or potentials which are of so small value as to be incapable of reducing a satisfactory indication in or inary indicating a paretus. The indicating appa rntus employc with the amplified currents or potentials may he of any convenient type, the particular-type employed being dependent upon. the character of theindicetion which it is desired to produce. If it is desiredto reduce a steady indication, such, for exa'mp e, as an indication of the voltage of a potential to be amplified an indicating instrumentof the galvanometer type may be employed.

In carrying my invention into effect I eniploytwo electron discharge amplifiers of the thine-electrode type. The potcntialsor currents to be amplified are impressed upon the grid circuits of the amplifiers in such a way that ihcnverogc current in the plate circuit of one cvicc is increased when the potential of the gird is varied and the aver age current in the plate circuit of the other device is caused to decrease. The desired indicntionis then produced by on indicating instrumenthaving two actuating coils which are included respectivcly jn the two .plnte circuits and arranged in such away that the indication produced varies with differences in the currents through the two 4 coils. I I r novel features which I believe to be charncteristicof my invention are set forth with particularity in the appended claims, rhy invention itself, however, both as to its Mi orgei'iizntion and method of operation will host be understood by reference to the following description tnlrcn in connection with the-accompanying drawing in which I have indicated dingrzurunoticclly one way in I the other coil.

which my invention may be carried into M effect. I

As indicated in this drawing, the am dillyingsystem comprises two electron discnergc devices 1 end 2 having the usual filamentary cathodes 3 and henode 5 end 6 end grids 2 {i0 andB. The id circuit of device )linclndes the source 0 olternating tenticl 9, which is to be amplified, rind a nttery 10in!) ed ustmg the normal. potential of the grid-'3 to the proper. value for-securing the desired operation of the device 1. The grid circuit of device 2 includesdhe source of ammo ing potential or current 9 and e series condenser 11 shunted by the grid leak resistenee 12. The battery 13 furnishes current i or m heating the cathodes 3 and 4, the regulation of the temperature of the two cathodes roe ing-eficcted in the usualway bymeans of variable resistances 14, 15. The plate circuit of device 1 includes a. source oi current lfi 'and' the coil 17 of an indicating instrument 18, which-may he the 'gelvanometer type. The plate circuit of device 2 includes tlge source 16 and the coil 19 of instrument 1 so In the operation of the'svstem SilQWiay' when an alternating potential from source 9 isimpressed upon the'grid circuits the average current in the grid circuit of the device -2 is caused to decrease. The battery 10 in the grid circuit of device 1 is edjusted to such a value that a positive potential impressed from source 9 upon the grid circuit of device 1 produces an appreciable increase in current, Whereas a negative potential will produce substantially no decrease in current of the plate circuit of device 1. It is there, fore apparent that the effect of impressing an alternating! potential upon the two grid circuits is to produce an increase in the average currc in the plate circuit of the device 1 and a decrease in the average current of the pl-etc circuit of device Q. The coils 17 end 19 of the indicating instrument 18 are so arranged that the force exerted upon the moving element of the instrument by one coil'is opposed to that exerted by The devices 1 and 2 are so adjusted that there is either no resultcnt deflection of. the instrument or that the dc- Hoction is of some fixed predetermined value. When an alternating potential is pressed upon the grid circults of the two devices the resultant change in the deflection of the-indicating instrument is due to the sum of the decrease of current in the device, 2 and the increase of current in the device 1. By proper calibration of the instrument 18 the resulting deflection may he made to indicate on a suitable scale a measure of the potential impressed upon the grid circuits of the two devices from the source 9 or of the current by which this potential is produced.

While I have illustrated and described a preferred embodiment of my invention, it is apparent that my. invention-is by no. means limited to the particular embodiment illus trated but that many modifications in the type and arrangement of the apparatus used and that the principle of operation involved may be utilized to furnish any desired sort alternatin of indication without departing from the scope of my invention asset forth in the appended claims.

' What I claim as new and desire to secure by Letters Patent of the United States, is

1. Means for producing an indication of potentials comprising a pair of electron discharge devices having plate and grid circuits associated therewith, means for applying the alternating potentials to be indicated to the grid circuits of said devices in such a way that the average current in v the plate circuit of one device will decrease and the. average current in the plate circuit of the other device will increase, and an indicating device associated with the plate circuits which is responsive to difierences in the average currents in the two plate circuits.

2. Means for producing an indication of alternating potentials comprising a pair of grid circuits associated therewith, means for applying the alternating potentials to be in dicated to the grid circuits of said devices in such a Way that the average current in the platocircuit of one device will decrease and the average current in the plate circuit of the other device will increase and an indicating device connected differentially to the plate circuits oi. the two devices.

4. Means for producing an indication of alternatin potentials comprising a pair of electron discharge devices having plate and grid circuits associated therewith, a source of potential connected to the grid'of one device for maintaining the grid of that device normally at 'a desired negative potential, a condenser shunted by a high, resistance in the grid circuit of the other device, means for applying the potentials to be indicated to a common portion of the grid circuits of said devices and an indicating de- Vice connected differentially to the plate i circuits of the two'devices.

In witness whereof, I have hereunto set my hand this 26th day of September,

' HARRY B. MARVIN. 

